1. Field of the Invention
This invention pertains generally to brakes and more particularly to safety devices for fluid pressure operated brakes.
2. Discussion of the Prior Art
Vehicular hydraulic brake systems typically include a master cylinder operative in response to force applied to a brake pedal by the vehicle operator. A reservoir, usually included as part of the master cylinder, retains an excess of brake fluid to be used in the system. The brake fluid, being a substantially noncompressible fluid, acts to distribute pressure throughout the system when the brake pedal is actuated. Factors such as wear on the brake pads or brake shoes due to repeated braking applications ultimately require added amounts of fluid in the system. Thus, the level of fluid in the reservoir is gradually lowered as the system requires more and more fluid. A diaphragm, placed in the reservoir aids in limiting contamination of the fluid due to dirt and other foreign matter which could impede or impain the system function and also as the fluid level in the reservoir is lowered, the diaphragm extends downward with the fluid level so as to correspondingly displace the volume of fluid leaving the reservoir.
Fluid level sensors are often used to indicate a predetermined minimum level of fluid in such reservoirs. One such sensor is immersed into the fluid and includes a float member which follows the fluid level. Thus the float must be free to move in the reservoir in order to maintain a fixed position relative to the lowering fluid level. Diaphragms, such as hereinabove described can interfere with the movement of the float member and if so will render the sensor unreliable. Also, with space in the reservoir being limited due to the presence of the sensor, the diaphragm is limited in its ability to move correspondingly in order to displace the fluid leaving the reservoir. Thus, further lowering of the fluid level without a corresponding extension of the diaphragm can cause an undesirable vacuum condition to exist in the reservoir which can prevent the brake system from drawing further amounts of fluid from the reservoir. It would be of benefit, therefore, to provide such a reservoir with a non-vacuum creating and non-float interferring relationship between the fluid level, the sensor and the diaphragm so as to avoid the abovementioned undesirable conditions.